i heard these heads are 58 cc. right?im pretty sure mine are the 64 cc right now,but they had a 3angle vavle job,how much higher compression would i have if i went with these heads?would it be to much for my engine?would i have to run high test all the time?im talkin bout the aluminum heads,thanks guys.
also,
im in the process of buying a 84 trans am,im picking it up this sun.
it has a 305 4 bbl,what modes do you think i should start with?i have a flowmaster exhaust from cat back,would like to get headers soon,but what would help out more after that?i could swap my tpi off my 86 onto it,but i just dont know bout all that,its maf,and i dont want to spend to much money on her,thanks for your help.

 

If you can run now with 64 cc cast iron heads with no detonation
without retarded timing or some other fuel guzzleing
compromize, you should be fine with 58cc aluminum heads.
Use the proper .051" Corvette Head gasket" designed for aluminum heads to install these heads.

Generally a motor with aluminum heads will tolerate about
a half a compression ratio greater than the same motor with
cast iron heads. going from 64 cc to 58cc on a 350 will increase the cr about .5 cr. When you also use the corvette gasket..(051)

But then that "3 angle valve job" well that could throw
a wrench into the whole plan..

 

Yeah remember that due to heat transfer of aluminum to iron, you can get away with about 4cc's and still have the same static comp ratio.

 

alright well that solves that problem,now,would you guys recommend these heads for my application?my engine is in my sig.how much more power will these give me?thanks.

 

Be careful using a super-thick head gasket...while it does reduce the net compression, it also makes the engine more prone to detonation. I did this very thing when I built my 355, flat top pistons and Vette 58cc heads. Got worried about all the compression, so I used the GM composition head gasket at 0.051" compressed thickness.

I'm not seeing a lot of spark knock running 89 octane gas an a spark table somewhere between stock and ARAP, but also leaving some HP behind unnecessarily.

Read thru Vizard's book on cylinder heads and he explains the effect of "squish" in the quench area...not enough squish (like with a really thick head gasket or excessive piston to deck clearance) and you're leaving fuel/air in the quench area to combust, whereas with more squish you shove it out into the combustion chamber where it can be burned.

 

The static compression does change when raising or lowering combustion chamber volume. Aluminum will pull more heat from the combustion area than iron, reducing the chance of detonation.

 

Well, heres some figures.

Bore = 4.030" = same = same
Stroke = 3.48" = same = same
Head cc's = 66 = 60 = same
Deck Height = .025" = same = same
H/Gasket Thick = .040" =.051" = .040
H/Gasket Bore = 4.166" = same = same

Comp/Ratio = 10.07 Comp/Ratio = 10.49 Comp/Ratio = 10.81
Deck Height = .065" Deck Height = .076" Deck Height = .065"

Well, when you look at these figures you had better say to your self, I better listen to "kevinc". Your eng. as it stands now with the .065" D/H is right on the edge of not having enough "Squish". The 10.49 eng. is out of the question because it will rattle its brains out because of that .076" D/H. The 10.81 (to run on pump gas) will need a very late closing int. valve to reduce cyl. pressure. Remember their are two compression ratios to consider, Mechanieal (the way we all figure it) and Effective (figured when the int. valve closes).

Auggie

 

The numbers do a much better job of illustrating the point, great post.

GM makes/sells a composition head gasket, specified for aluminum heads with 0.028" compressed thickness and the smallest fire ring diameter I found at the time (4.100" versus the Felpro 1010's 4.166"). Part# is 10105117.

It appears to be the stock piece for L98 Vettes with aluminum heads...and will be what goes on when the FastBurn heads go on this Winter.